Cellulose acetate spinning solutions



United States Patent 3,068,063 CELLULOSE ACETATE SPINNING SOLUTIONS CONTAINING ZHRCONIUM ADDITIVES John E. Kiefer and George P. Touey, Kingsport, Tenn.,

assignors to Eastman Kodak Company, Rochester,

N.Y., a corporation of New Jersey No Drawing. Filed Oct. 25, 1960, Ser. No. 64,746 5 Claims. (Cl. 1854) This invention concerns a new spinning solution and the process of spinning such solution into fine denier filaments. More particularly, this invention concerns the incorporation of relatively small amounts of certain zirconium compounds into cellulose acetate spinning solutions whereby the viscosity of the cellulose acetate solution is increased in a manner that facilitates the spinning of fine denier filaments therefrom.

This application is related to and is a continuation in part of our companion copending applications Serial Numbers 848,187 and 848,188.

As set forth in our companion applications, in the production of cellulose acetate yarn, cellulose acetate is dissolved in acetone or the like solvent. The spinning dope is put under pressure and forced through small holes or orifices in a spinneret. The fine strands of dope are continuously pulled from the spinneret through a spinning cabinet where the solvent is evaporated by means of hot air. The denier of the resulting filaments can be defined by the factors of dope solids, draft, dope density, and orifice diameter as follows:

Denier per filament K (dope percent solids) (orifice diameter) (dope density) take-up divided by the linear extrusion speed of the spinning solution at the orifice. In many instances spinning draft is limited to about 1.8. Excessive draft can result in many broken filaments and filaments with reduced physical properties.

The above relationship suggests changing the orifice diameter as a means of varying the denier of cellulose acetate filaments. However, when spinnerets with orifices with diameters less than about 0.035 mm. are used, mechanical difiiculties may arise in the spinning operation. The acetate spinning dope does not flow through the smaller holes at an even rate and the holes tend to become clogged.

The denier of cellulose acetate filaments can also be varied by varying the solids content of the spinning dope. It is apparent that lowering the solids concentration of a dope will decrease the denier of the resulting filament, assuming the extrusion rate and the take-up rate are held constant. However, when the solids content of cellulose acetate is decreased, the dope viscosity also decreases. This produces difficulties in controlling the proper flow rate of the dope through the spinneret. Also, dopes with low viscosity may tend to stick to the metal spinneret and are, therefore, difiicult to pull into filaments. One method of eliminating this problem is to use a cellulose acetate with a higher intrinsic viscosity than is normally used for cellulose acetate yarn. The higher cost of producing a high intrinsic viscosity ester has tended to make this approach unattractive. H

In recent years there has developed a market for fine denier filaments. One particular use therefor is the manufacture of tobacco smoke filters from such fine denier cellulose acetate filaments. It is apparent, therefore, that the development of simple, less expensive procedure for making such cellulose acetate filaments represents a highly desirable result.

After extensive investigation we have discovered a relatively simple way by which such fine denier filaments may be produced without involving the change of presently used spinning equipment or other material changes in existing processes for producing cellulose acetate filaments.

This invention has for one object to provide a cellulose acetate spinning solution of increased viscosity but with relatively low solids content. Still another object is to provide a way of improving cellulose acetate spinning solutions whereby they may be more readily spun into fine denier filaments. A particular object is to provide a cellulose acetate spinning solution which has a relatively small amount of certain zirconium compounds therein. Still a furtherobjectis to provide a method for spinning cellulose acetate filaments of relatively small deniers such as deniers of the order of 0.2-2 denier per filament. Other objects will appear hereinafter.

In the broader aspects of our invention we have found that commercial yarn grade cellulose acetate spinningdope diluted with acetone or equivalent solvents to a low solids content (15-23%), which concentration is notnormally suitable for spinning, can be made suitable for spinning by the addition of 0.02 to 1.5% (based on the cellulose acetate) of zirconium chelate esters. Such zirconium compounds apparently partially affect the cellulose acetate in some manner which results in a large increase in the viscosity of the cellulose acetate spinning dope. The large increase in dope viscosity, on addition of very small amounts of zirconium chelates, was quite unexpected.

Therefore, the present invention may be accomplished by adding 0.01 to 1.00% (based on the cellulose acetate) of a zirconium chelate to a low solids cellulose acetate spinning dope, then spinning the dope into fibers using conventional cellulose acetate spinning equipment.

The zirconium chelates useful in carrying out this invention are those chelates which are acetone soluble, are

fairly resistant to hydrolysis (most cellulose acetate spinning dopes contain some water) and which react with the free hydroxyl groups of the cellulose acetate. They have the following composition.

where x=0, 1, 2, or 3 and R represents an alkyl or aryl hydrocarbon such as the ethyl, propyl, butyl, Z-ethylhexyl, or phenyl group. R represents an oxy compound capable of chelating with zirconium such as dihydroxy, diketo, hydroxyketo compounds, hydroxycarboxylic acids and their esters, and ketocarboxyli-c acids and. their esters. Examples of the oxy chelating compounds useful in carrying out this invention are acetyl acetone, ethyl acetoacetate, diacetone alcohol, 1,3-octylene glycol, and ethyl lactate. V

The cellulose acetate which can be used in carrying out this invention comprises yarn grade acetone soluble cellulose acetate With an acetyl content of 37-42%. The cellulose acetate spinning'dopes which are preferred for use in carrying out this invention consist of 10 to 23% cellulose acetate, 76 to 89% acetone, .5 to 3% water and 0.01 to 0.50% (based on the cellulose acetate) of the zirconium chelate.

A further understanding of our invention will be ap While we prefer to operate with acetone solutions of cellulose acetate, since as is well known acetone is the common readily available commercial solvent frequently used for dissolving cellulose acetate as illustrated above, our invention will function when other solvents are used parent from the several examples which follow for illustrating certain of our preferred embodiments. for the cellulose acetate. Accordingly, our invention is EXAMPLE I not limited to the particular cellulose acetate acetone solutions described above.

A c ll 1 t t f 20% 3 2: 225;; 513 g gfgs ii figgg g Fine denier filaments produced in accordance with thls divided into 1 kg samples one Sample was used as a 1 invention have utility for various purposes such as in the control. Zirconium chelate additive compounds of the fg fl i i l d d t present invention were added to the other samples. Each e mventon Ben e 8 a1 W1 dope was then mixed 30 minutes. The viscosity of the i f refinance to prefarred qmpodlmems theicofibut dopes was measured with a Brookfield viscometer The ll. will be understood that variations and modlfications dopes were stored at room temperature and the viscosity be effectiad W1th1n.the Spmt and Scope of Invenwas redetcrmined at intervals. The results shown on mm as (165? nbed heremabove and as defined m the ap- Table 1 illustrate how zirconium complexes affected the gg fl w viscosities of these dopes. The data indicates that the 1 11 11 f 611w zirconium chelate increases the viscosity of the cellulose l z 22 9 essen 1a foircconb acetate very rapidly. Following this initial increase of 05c 2? so ven are ore i an 2 2 1 viscosity no further change in the dope is apparent. we ate compound of age on l e weight of the cellulose acetate, said chelate compound EXAMPLE II falling under the empirical formula:

A cellulose acetate spinning dope consisting of 20% (Rmxzrmoh cellulose acetate, 78% acetone and 2% water was di- 2 g vided into twO Portions one portion was Spun using wherein x TPYESSHLS a figure from the group consisting a conventional cellulose acetate spinning cabinet. A spini 2 and R represams a group from the class neret with orifices with a 0.035 mm. diameter was used. 515mg of ethyl propyl butyl z'ethylhexyl and pheilyl The spinning draft was maintained at 1.5. The dope n repliesents an ({Xywmpound .caijable of.chelatmg stuck to the face of the spinneret, stopping up the orifices. i zlrcomurfl from me group f l f dlhydmxy No filaments with satisfactory tensile properties were dmeto hydmky keto l y calbmyhqaclds and their obtained esters and keto carboxyhc acids and their esters.

To seflond portion of the dope was added fmm 2. The method for producing a cellulose acetate spintenths percent (based on the cellulose acetate weight) nmg Solunon of higher vlscoslty Whlch comprises adding Zirzonium ethyl acetoacemte chelate 3V 0.02 to 1.5%, based on the weight of the cellulose acetate,

Z 0C H CH C0 60 H 0 a zirconium material chelated with a material from the r( 7)2( 3 group consisting of octylene glycol, ethyl acetoacetate, diwith suitabl l g on g, the VISCOSIW the acetone alcohol and ethyl lactate, to a solution which con- P lncfeflsfid from 12,100 P I0 4 D Thls P tains as essential ingredients cellulose acetate and acetone. was spun into yarn using a conventional cellulose acetate 3, Th th d f making fine denier filaments which Spllmmg cablllet- A p Wlth Wlth a @035- comprises forming a spinning solution containing cellumm. diameter was used. The 1.02 denier per filament lose acetate 15-23%, 0.02 to 1.5% based on the weight 31 Obtfimed had a $115110 Strength of grams P of the cellulose acetate of a zirconium chelate having the denier and an elongation of 24%. properties of dissolving in the spinning solution solvent,

EXAMPLE III causing an increase in viscosity of the spinning solution A cellulose acetate spinning dope consisting of 15% as well as being resistant to hydrolysis and wherein the Cellulose acetate, 83% acetone 2% Water had a viscosity ZllCOl'llLlfl'l chelate consists of z rconium chealted with a of 6320 The dope could not be spun into filaments material from the group consisting of octylene glycol, using conventional techniques. Five-tenths percent (based ethyl acetoacfilate, dlacfitolle al hol and ethyl lactate. on the cellulose acetate weight) zirconium tetrakis acetylmefthod accordance. wlth clam 3 whefem acetonate (prepared by the method described by the solution 1s forced through spinneret holes of a diam- Blumenthal, chemical Bahavior of Zirconium, eter not substantially greater than 0.035 mm. and with- Van Nostrand Coa Princeton, New Jamey, 1958, 367), drawing the filaments formed at a draft not greater than was added to the dDIm The viscosity increased to 38,500 about 1.8 and into an atmosphere which evaporates the cps. The dope was then spun into yarn usin a conven- 5 Solvent tional spinning cabinet. A soinneret with 0.0%5-mm. orio The m a?cordance l Claim 3 wherein the fleas and a spinning draft I 15 was usd seventy six amount of the zirconium chelate is less than 1.00%. hundredths denier per filament yarn was obtained. It R f e Cited in the fil f this patent had a tensile stren th of 1.21 rams er denier and. an elongation of g p UNITED STATES PATENTS The data appearing in the following table will further 2,072,102 Drefus Mar. 2, 1937 illustrate the feature of increasing the viscosity and the 2,615,860 Burgess Oct. 28, 1952 constantnature thereof. 2,680,108 Schmidt June 1, 1954 Table I Cor'tcentra- Viscosity, Ops. Alter- Viscosity Modifier (Bus gd on Cell lose Acetate 30 Min. 1 Day 30 Days Weight) No additive (control) 12,100 12, 300 12, 400 Zirco ium et yl acetoacetatc 0.2 26,400 26, 900 27,100 Z1(OC4H9)2(CH3COCH:COOC2H5) Zirconium tetrakis aeetylacetonate-.. 0.2 19,700 20. 200 20,100 

1. A SPINNING SOLUTION CONSISTING ESSENTIALLY OF CELLULOSE ACETATE SOLVENT THEREFORE AND AN AMOUNT OF ZIRCONIUM CHELATE COMPOUND OF 0.0I TO 1.5% BASED ON THE WEIGHT OF THE CELLULOSE ACETATE, SAID CHELATE COMPOUND FALLING UNDER THE EMPIRICAL FORMULA: 